Ethylene-vinyl alcohol copolymer composition pellets, and production method for ethylene-vinyl alcohol copolymer composition pellets

Patent metadata

Field	Value
Publication number	US-2019322817-A1
Application number	US-201916451581-A
Country	US
Kind code	A1
Filing date	Jun 25, 2019
Priority date	Dec 28, 2016
Publication date	Oct 24, 2019
Grant date	—

Abstract

Ethylene-vinyl alcohol copolymer composition pellets comprise: an ethylene-vinyl alcohol copolymer, a conjugated polyene, and a predetermined amount of at least one fisheye-suppressing component; wherein pellet surface portions of the ethylene-vinyl alcohol copolymer composition pellets have a conjugated polyene content of not lower than 30 ppb based on the weight of the pellets. Such ethylene-vinyl alcohol copolymer composition pellets are capable of reliably suppressing occurrence of minute fisheyes having a diameter of 200 μm or smaller.

First claim

1 . Ethylene-vinyl alcohol copolymer composition pellets comprising:
an ethylene-vinyl alcohol copolymer; a conjugated polyene; and at least one component selected from the group consisting of: (A) 10 to 400 ppm of a lubricant based on a weight of the ethylene-vinyl alcohol copolymer composition pellets; (B) 10 to 250 ppm of a boron compound based on the weight of the ethylene-vinyl alcohol copolymer composition pellets; and (C) 1 to 500 ppm of an alkali metal based on the weight of the ethylene-vinyl alcohol copolymer composition pellets; wherein pellet surface portions of the ethylene-vinyl alcohol copolymer composition pellets have a conjugated polyene content of not lower than 30 ppb based on the weight of the ethylene-vinyl alcohol copolymer composition pellets.

2 . The ethylene-vinyl alcohol copolymer composition pellets according to claim 1 , wherein the conjugated polyene content of the pellet surface portions is determined by dissolving 20 g of the ethylene-vinyl alcohol copolymer composition pellets in 30 mL of a mixed solvent having a water/methanol volume ratio of 1/1 with stirring for 10 minutes, and dividing the conjugated polyene amount contained in a resulting solution by the weight of the ethylene-vinyl alcohol copolymer composition pellets.

3 . The ethylene-vinyl alcohol copolymer composition pellets according to claim 1 , which have an overall conjugated polyene content of 0.1 to 10,000 ppm based on the weight of the pellets.

4 . The ethylene-vinyl alcohol copolymer composition pellets according to claim 1 ,
wherein a weight-based content ratio (surface conjugated polyene content/overall conjugated polyene content) between the conjugated polyene content of the pellet surface portions of the ethylene-vinyl alcohol copolymer composition pellets and the overall conjugated polyene content of the ethylene-vinyl alcohol copolymer composition pellets is not lower than 1.5×10 −5 .

5 . The ethylene-vinyl alcohol copolymer composition pellets according to claim 1 ,
wherein the conjugated polyene is at least one selected from the group consisting of sorbic acid, a sorbic acid ester, and a sorbic acid salt.

6 . A method for producing the ethylene-vinyl alcohol copolymer composition pellets according to claim 1 , comprising:
bringing pellets of an ethylene-vinyl alcohol copolymer into contact with a treatment liquid containing a conjugated polyene; and bringing the ethylene-vinyl alcohol copolymer pellets into contact with at least one component selected from the group consisting of a lubricant, a boron compound, and an alkali metal.

7 . The ethylene-vinyl alcohol copolymer composition pellet production method according to claim 6 , wherein the ethylene-vinyl alcohol copolymer pellets are prepared by solidifying and pelletizing an alcohol solution or a water/alcohol mixed solution of the ethylene-vinyl alcohol copolymer.

8 . The ethylene-vinyl alcohol copolymer composition pellet production method according to claim 6 , wherein the ethylene-vinyl alcohol copolymer pellets are porous ethylene-vinyl alcohol copolymer pellets.

9 . The ethylene-vinyl alcohol copolymer composition pellet production method according to claim 6 ,
further comprising adding the conjugated polyene as a polymerization inhibitor to an ethylene-vinyl ester copolymer and then saponifying the ethylene-vinyl ester copolymer to prepare the ethylene-vinyl alcohol copolymer.

Assignees

• Mitsubishi Chem Corp

Inventors

• SENO Ryuta
• Hatanaka Makoto

Classifications

• C08L23/0815

  with aliphatic 1-olefins containing one carbon-to-carbon double bond · CPC title

• C08L2205/025

  containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure · CPC title

• C08L2203/10

  used for bottles · CPC title

• C08K5/09

  Carboxylic acids; Metal salts thereof; Anhydrides thereof · CPC title

• C08J2329/04

  Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids · CPC title